| 1. |
- Hansson, Anders P, et al.
(författare)
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Right atrial free wall conduction velocity and degree of anisotropy in patients with stable sinus rhythm studied during open heart surgery
- 1998
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Ingår i: European Heart Journal. - : Oxford University Press (OUP). - 1522-9645 .- 0195-668X. ; 19:2, s. 293-300
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: Although the perpetuation of several supraventricular arrhythmias is critically dependent upon intra-atrial conduction, the literature lacks detailed information on normal values of conduction velocity and degree of anisotropy. In order to explore these factors further, we have measured conduction velocities at the right atrial free wall during sinus rhythm and during atrial pacing in four directions parallel and perpendicular to the atrioventricular groove in patients with normal atria and stable sinus rhythm. METHODS AND RESULTS: Using a Bard Cardiac Mapping System, atrial ECGs were recorded using a 3 x 4 cm electrode array with 56 equally spaced bipolar electrodes in 12 patients undergoing open heart surgery due to ischaemic heart disease or Wolf-Parkinson-White syndrome. A bipolar pen probe connected to a Medtronic 5328 stimulator was used for pacing at a 10% higher rate than sinus rhythm. The local activation times were manually set and isochronal activation maps were created for each recording. The conduction velocities were calculated from the activation maps over a distance ranging from 2.2 to 4.2 cm. The majority of the activation maps showed no signs of anisotropy; the others had less than 15% spatial inhomogeneity of conduction. Mean conduction velocity, calculated from five consecutive beats, was 88 +/- 9 cm.s-1 (mean +/- SD), ranging between 68 +/- 4 and 103 +/- 3 cm.s-1 during sinus rhythm. Mean conduction velocity during atrial pacing was 81 +/- 16 cm.s-1 at a propagation direction of 0 degree, 74 +/- 14 cm.s-1 at a 90 degrees direction, 79 +/- 12 cm.s-1 at 180 degrees and 78 +/- 20 cm.s-1 at 270 degrees, where 0 degree was parallel to the atrioventricular groove in the cranial direction and the angle increased counter-clockwise. Mean conduction velocity during sinus rhythm was significantly higher (P < 0.05) than during atrial pacing at the 90 degrees and 180 degrees directions but not compared to atrial pacing at 0 degree or 270 degrees. There was no significant difference in mean conduction velocity in different directions during atrial pacing. CONCLUSION: Although anisotropy was documented during conduction velocity in individual cases, conduction velocity was not dependent on propagation direction at the epicardial right atrial free wall in patients with stable sinus rhythm. These findings do not exclude the presence of internodal preferential pathways as these are located sub-epicardially and a marked transmural discordance in activation has previously been documented in the vicinity of such pathways.
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| 2. |
- Holm, Magnus, et al.
(författare)
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Epicardial right atrial free wall mapping in chronic atrial fibrillation. Documentation of repetitive activation with a focal spread--a hitherto unrecognised phenomenon in man
- 1997
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Ingår i: European Heart Journal. - : Oxford University Press (OUP). - 1522-9645 .- 0195-668X. ; 18:2, s. 290-310
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Previous studies have shown that atrial fibrillation of recent onset in man is based on a varying number of simultaneously present activation waves reentering either themselves or each other. In the present study, right atrial activation during chronic atrial fibrillation in man was studied. METHODS AND RESULTS: In 16 patients with chronic atrial fibrillation multiple epicardial recordings of 8 s each were made at the right atrial posterior free wall and at the appendage using a 20 x 35 mm electrode array with 56 bipolar measurement points. The preferable activation pattern of each recording and the propagation direction, cycle length and conduction velocity of individual activation waves within each recording were determined. Activation was characterized by unorganised activation with several simultaneously present activation waves: inconsistent preferable activation pattern (n = 5), predominantly organised activation with either frequent episodes of uniform activation: consistent preferable activation pattern (n = 7) or frequent episodes of activation with focal spread; focal preferable activation pattern (n = 4). Random re-entry was frequently documented in recordings with the inconsistent preferable activation pattern and less frequently in recordings with the consistent and focal preferable activation pattern. Complete re-entry circuits were rarely documented. The median fibrillation cycle length was 146, 159 (P < 0.05) and 165 ms (not significant) and the mean conduction velocity during uniform activation was 64, 67 and 83 cm. s-1 (not significant) in recordings with the inconsistent, consistent and focal preferable activation pattern, respectively. CONCLUSIONS: During chronic atrial fibrillation in man, right atrial free wall activation ranges from disorganised activation with multiple co-existing activation waves to predominantly organised activation characterized by either uniform activation consistent with the presence of large re-entry circuits or repetitive activation of unknown mechanism and focal spread.
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| 3. |
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| 4. |
- Pehrson, Steen, et al.
(författare)
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Non-invasive assessment of magnitude and dispersion of atrial cycle length during chronic atrial fibrillation in man
- 1998
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Ingår i: European Heart Journal. - : Oxford University Press (OUP). - 1522-9645 .- 0195-668X. ; 19:12, s. 1836-1844
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: Atrial fibrillation cycle lengths can be assessed from right precordial ECG leads and the unipolar oesophageal ECG using a non-invasive method called Frequency Analysis of Fibrillatory ECG. The purpose of this report is to present the results from application of this method in a large group of patients with long-term atrial fibrillation and to examine the differences between patients with 'coarse' and 'fine' atrial fibrillation. METHODS AND RESULTS: Simultaneous 15 min recordings from V1, V2 and an oesophageal lead at a position behind the posterior atrium were obtained in 28 patients, aged 41 to 78 years, with long-term (> 1 month) atrial fibrillation. In each lead, using the time averaging technique, the QRST complexes were suppressed. Thereafter, the frequency distribution of the residual ECG was estimated by means of Fast Fourier Transform. In the 3-12 Hz range of each lead, the dominant atrial cycle length, the power maximum and the spectral width were calculated. In 26 patients (93%), frequency spectra in the 3-12 Hz range could be obtained. The dominant atrial cycle length ranged from 120 to 175 ms, mean 150+/-16 (SD) ms in V1, and from 120 to 190 ms, mean 150+/-16 in an oesophageal lead (ns). The absolute difference in the dominant atrial cycle length between V1 and the oesophageal lead was 10.4+/-7.7 ms. There was no significant difference in the dominant atrial cycle length in V1 between patients with coarse and fine atrial fibrillation. The power maximum in V1 was significantly greater in patients with coarse compared to fine atrial fibrillation (P=0.01). The spectral widths ranged from 10 to 55 ms and demonstrated significantly higher mean values in lead V2 compared to V1 (P=0.001). Compared to V1, the mean values tended to be smaller in the oesophageal lead (P=0.05). CONCLUSIONS: Using the Frequency Analysis of Fibrillatory ECG method, the dominant atrial cycle length, power maximum and spectral width can be estimated from the frequency spectra in the majority of patients with atrial fibrillation. Spatial dispersion of the dominant atrial cycle length occurs in some patients and may be an important proarrhythmic marker. The distinction between coarse and fine atrial fibrillation cannot be used as a marker of the atrial cycle length.
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| 5. |
- Roijer, Anders, et al.
(författare)
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Potential cardioembolic sources in an elderly population without stroke. A transthoracic and transoesophageal echocardiographic study in randomly selected volunteers
- 1996
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Ingår i: European Heart Journal. - 1522-9645. ; 17:7, s. 1103-1111
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Tidskriftsartikel (refereegranskat)abstract
- Transoesophageal echocardiography renders a better image than transthoracic echocardiography of cardiac changes especially at the atrial level, and of atherosclerotic changes in the aorta. Although several studies on stroke patients have included transthoracic and transoesophageal echocardiography, the relevance of the reported findings remains unclear because of limited information on the prevalence of cardiac changes related to cardioembolism in a control population without stroke. In order to define a non-hospitalized group of volunteers without previous stroke or transient ischaemic attack, we randomly selected a group of 68 volunteers (mean age 65.4 years). These volunteers were divided into two groups: the elderly group, 65 years or older (n = 38) and the younger group, younger than 65 years (n = 30). The subjects underwent transthoracic and transoesophageal echocardiography, sonography of the carotid arteries, and magnetic resonance imaging of the brain. The prevalences of atrial septal aneurysm, patent foramen ovale, mitral annulus calcification, and protruding plaque in the aorta were investigated. We found atrial septal aneurysm in 13%, patent foramen ovale in 22%, protruding plaque in the aorta in 7%, and mitral annular calcification in 22% of the 68 subjects. No significant differences were found between the two age groups with the exception of mitral annular calcification, which was seen more often in the older group (P < 0.001). Total cardiac changes related to thromboembolism (including three cases with atrial fibrillation in the older group and other less common cardiac embolic sources) were more common in the older than in the younger group (23/38 vs 9/30; P < 0.05). If mitral annular calcification was excluded, no difference was found between the elderly and the younger group, 14/38 vs 8/30; ns. Even when subjects with a history of heart disease or a pathological ECG were omitted, no differences between the two age groups were found. The causal relationship between a possible embolic source and a clinical embolic event remains unsettled. The high prevalence of cardiac changes in a control population has to be considered when evaluating the significance of similar findings in patients with stroke.
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| 6. |
- Yuan, S, et al.
(författare)
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The dispersion of repolarization in patients with ventricular tachycardia. A study using simultaneous monophasic action potential recordings from two sites in the right ventricle
- 1995
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Ingår i: European Heart Journal. - : Oxford University Press (OUP). - 0195-668X .- 1522-9645. ; 16:1, s. 68-76
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Tidskriftsartikel (refereegranskat)abstract
- The role of increased dispersion of repolarization in the genesis of torsade de pointes and ventricular fibrillation has been well recognized generally, but not in the genesis of monomorphic ventricular tachycardia (VT). Monophasic action potentials (MAP) were therefore recorded simultaneously from the right ventricular (RV) apex (RVA) and outflow tract (RVOT) during sinus rhythm, RV pacing and programmed extra stimulation (PES) in 24 patients with VT. The activation time (AT), MAP duration at 90% repolarization (MAPd), and repolarization time (RT) were measured and their dispersions, defined as the differences in these parameters between RVA and RVOT, were calculated. During sinus rhythm and RV pacing, the dispersions of AT, MAPd and RT (dispersions) were significantly larger in the 17 patients with a VT induced than in those without. During PES, the dispersions were further augmented in the S2 beats in the seven patients with a sustained VT induced, the maximal dispersion of RT being 85 +/- 22 ms. Both the dispersion of AT and that of MAPd contributed to the dispersion of RT. In both of our two patients with a sustained VT induced during MAP recording, a marked increase in dispersions of RT (140 and 190 ms, respectively) was observed immediately before the initiation of the VT. A link between the dispersions and the inducibility of a monomorphic VT was found in our patients, which suggests that the increased dispersions play an important role in the genesis of a monomorphic VT.
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